User's Guide
SLVU229A – February 2008 – Revised May 2009
Power-Distribution Switch With Adjustable Current-Limit
EVM
This user’s guide describes the TPS255xDBVEVM-271 and TPS255xDRVEVM-271 evaluation modules
(EVM). This guide contains the EVM schematic, bill of materials, assembly drawing, and top and bottom
board layouts.
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4
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Contents
Introduction ...................................................................................................................
1.1
Related Documentation from Texas Instruments ...............................................................
Electrical Specifications .....................................................................................................
2.1
Electrostatic Discharge .............................................................................................
Schematic and Bill of Materials ............................................................................................
3.1
EVM Options ........................................................................................................
3.2
Schematic ............................................................................................................
3.3
Bill of Materials ......................................................................................................
EVM Setup....................................................................................................................
4.1
Recommended Test Equipment ..................................................................................
4.2
Measuring the Short-Circuit Output Current-Limit .............................................................
4.3
Adjusting the Short-Circuit Output Current-Limit................................................................
Board Layout .................................................................................................................
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6
List of Figures
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2
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8
EVM Schematic ..............................................................................................................
EVM Setup For Measuring Current-Limit .................................................................................
TPS2551DRVEVM-271 Short-Circuit Output Current and FAULT Status With J2 Shorting Jumper Present. ..
TPS2551DRVEVM-271 Short-Circuit Output Current and FAULT Status With J2 Shorting Jumper
Absent. .......................................................................................................................
EVM Top Assembly .........................................................................................................
EVM Top-Side Layout .......................................................................................................
EVM Bottom-Side Layout ...................................................................................................
EVM Bottom Assembly......................................................................................................
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List of Tables
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3
EVM Electrical Specifications .............................................................................................. 2
EVM Options ................................................................................................................. 2
EVM Bill of Materials ....................................................................................................... 3
SLVU229A – February 2008 – Revised May 2009
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Power-Distribution Switch With Adjustable Current-Limit EVM
1
Introduction
1
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Introduction
The TPS255xDBVEVM-271 and TPS255xDRVEVM-271 are evaluation modules (EVM) for Texas
Instruments’ family of power-distribution switches with adjustable current-limit. These EVMs operate over a
2.5-V to 6.5-V range. An onboard jumper sets the output current-limit to either 0.5 A or 1 A. Test points
provide convenient access to all critical node voltages.
The silkscreen outline on the PCB top-side encloses components found in a typical USB application.
The PCB top-side accepts a power-distribution switch in a SOT23-6 package; the PCB bottom side
accepts a power-distribution switch in the smaller SON package with a thermal pad. These switches have
an enable input, an overcurrent status output, and overtemperature shutdown.
1.1
Related Documentation from Texas Instruments
TPS2550, TPS2551 data sheet (SLVS736)
2
Electrical Specifications
The EVM meets the electrical specifications in Table 1 over the recommended operating
junction-temperature range of -40°C ≤ Tj ≤ 105°C for the DRV (SON) package and -40°C ≤ Tj ≤ 125°C for
the DBV (SOT23-6) package.
Table 1. EVM Electrical Specifications
2.1
Parameter
Condition
Input voltage, Vin
J1
Min
Short-Circuit Output
Current-Limit, ILIMIT
J2 shorting-jumper is absent, J3 is short
circuited, TPS255x is enabled
0.60 0.65 0.72 Ampere
J2 shorting-jumper is present, J3 is short
circuited, TPS255x is enabled
1.20 1.28 1.38
2.5
Typ Max
–
Unit
6.5
Volt
Electrostatic Discharge
The EVM has been tested to IEC 61000-4-2. The level used was 8-kV contact discharge and 15-kV air
discharge. Surges were applied to the EVM input and output. No damage to the TPS255x was observed.
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Schematic and Bill of Materials
3.1
EVM Options
Table 2. EVM Options
2
EVM
Device
Device Package
Enable
TPS2550DBVEVM-271
TPS2550DBV
SOT23-6
Active Low
TPS2551DBVEVM-271
TPS2551DBV
SOT23-6
Active High
TPS2550DRVEVM-271
TPS2550DRV
SON
Active Low
TPS2551DRVEVM-271
TPS2551DRV
SON
Active High
Power-Distribution Switch With Adjustable Current-Limit EVM
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EVM Setup
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3.2
Schematic
+
See Table 3.
Figure 1. EVM Schematic
3.3
Bill of Materials
Table 3. EVM Bill of Materials
QTY
-001
RefDes
Value
Description
Size
Part Number
MFR
-002 -003 -004
1
1
1
1
C1
10µF
Capacitor, Ceramic, 10-µF, X7R, 10V, 10%
1206
STD
STD
2
2
2
2
C2, C3
0.1µF
Capacitor, Ceramic, 16V, X7R, 10%
0805
STD
STD
1
1
1
1
C4
150µF
Capacitor, Tantalum, 150µF, 10V, 100mΩ,
10%
7343 (D)
B45197A2157K409
Kemet
1
0
0
0
U1
TPS2550DBV
IC, Power-Distribution Switch,
Current-Limited
SOT-23-6
TPS2550DBV
TI
0
1
0
0
U1
TPS2551DBV
IC, Power-Distribution Switch,
Current-Limited
SOT-23-6
TPS2551DBV
TI
0
0
1
0
U2
TPS2550DRV IC, Power-Distribution Switch,
Current-Limited
SON
TPS2550DRV
TI
0
0
0
1
U2
TPS2551DRV IC, Power-Distribution Switch,
Current-Limited
SON
TPS2551DRV
TI
1
1
1
1
--
HPA271
PCB, 2.25 In × 2.225 In × 0.062 In
HPA271
Any
2
2
2
2
R1, R2
10.0K
Resistor, Chip, 1/10W, 1%
0805
CRCW0805-1002F
Vishay
2
2
2
2
R3, R4
20.0K
Resistor, Chip, 1/10W, 1%
0805
CRCW0805-2002-F
Vishay
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EVM Setup
4.1
Recommended Test Equipment
The following test equipment is recommended:
• Two-channel storage oscilloscope
• Current probe
• Voltage probe
• An adjustable power supply with a 2.5-V to 6.5-V output and a 5-A output current-limit
• Volt-ohm meter
SLVU229A – February 2008 – Revised May 2009
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EVM Setup
•
4.2
www.ti.com
A passive or active load capable of handling 3 A.
Measuring the Short-Circuit Output Current-Limit
The user should read the TPS2550/1 data sheet before using the EVM.
Figure 2 shows the EVM test setup for measuring current-limit. Switch S1 enables the power-distribution
switch into a short circuit for this measurement. Figure 3 shows the current waveform for the
TPS2551DRVEVM-271 with a shorting jumper populating header J2; Figure 4 shows the current
waveform with header J2 unpopulated.
Oscilloscope
Voltage Probe
FAULT
Current
Probe
+
IN
-
5V, 5A
EVM
+
OUT
-
0-W
7" Twisted Pair, #20AWG
Figure 2. EVM Setup For Measuring Current-Limit
FAULT#
ILIMIT
lin
Figure 3. TPS2551DRVEVM-271 Short-Circuit Output Current and
FAULT Status With J2 Shorting Jumper Present.
4
Power-Distribution Switch With Adjustable Current-Limit EVM
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EVM Setup
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FAULT#
ILIMIT
lin
Figure 4. TPS2551DRVEVM-271 Short-Circuit Output Current and
FAULT Status With J2 Shorting Jumper Absent.
4.3
Adjusting the Short-Circuit Output Current-Limit
The EVM provides two current-limit settings. If a different setting is required, then populate header J2 with
a shorting jumper and modify resistor R3 according to Equation 1:
1
1.114
R3 =
28700
(ILIMIT
)
(1)
Where: 15 kΩ ≤ R3 ≤ 80.6 kΩ.
The current-limit programming resistance, R3, is expressed in kΩ and the typical current-limit, ILIMIT, is
expressed in mA. See the TPS2550/1 data sheet for the worst-case current-limit variation.
SLVU229A – February 2008 – Revised May 2009
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Power-Distribution Switch With Adjustable Current-Limit EVM
5
Board Layout
5
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Board Layout
Figure 5. EVM Top Assembly
Figure 6. EVM Top-Side Layout
6
Power-Distribution Switch With Adjustable Current-Limit EVM
SLVU229A – February 2008 – Revised May 2009
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Board Layout
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Figure 7. EVM Bottom-Side Layout
Figure 8. EVM Bottom Assembly
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7
EVALUATION BOARD/KIT IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES
ONLY and is not considered by TI to be a finished end-product fit for general consumer use. Persons handling the product(s) must have
electronics training and observe good engineering practice standards. As such, the goods being provided are not intended to be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental
measures typically found in end products that incorporate such semiconductor components or circuit boards. This evaluation board/kit does
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Should this evaluation board/kit not meet the specifications indicated in the User’s Guide, the board/kit may be returned within 30 days from
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Please read the User’s Guide and, specifically, the Warnings and Restrictions notice in the User’s Guide prior to handling the product. This
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FCC Warning
This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES
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EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input voltage range of 2.5 V to 6.5 V and the output voltage range of 2.5 V to 6.5 V.
Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions
concerning the input range, please contact a TI field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM.
Please consult the EVM User's Guide prior to connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than 85°C. The EVM is designed to operate
properly with certain components above 85°C as long as the input and output ranges are maintained. These components include but are
not limited to linear regulators, switching transistors, pass transistors, and current sense resistors. These types of devices can be identified
using the EVM schematic located in the EVM User's Guide. When placing measurement probes near these devices during operation,
please be aware that these devices may be very warm to the touch.
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